Yejin Lee

Ergonomic mapping of skin deformation in dynamic postures to provide fundamental data for functional design lines of outdoor pants

Outdoor brands often use streamlined cutting lines to design high-performance outdoor pants. Inappropriate design lines combined with the accompanying sewing lines can cause discomfort or even restrict body movement. To reduce such discomfort, we need to find the appropriate location for cutting lines that do not interfere with body movement. In this research, we conducted ergonomic mapping of skin deformation in dynamic postures to provide fundamental data for selecting functional design lines of pants that will not hinder various movements. To analyze the lower body skin deformation depending on the posture, we marked dots at 3 cm intervals on the leg. We then measured the change in length between the points for three different postures using a three-dimensional scanner and the Rapidform program. The results were shown as a skin deformation map; this is expected to be used as reference data for the functional design lines of streamlined outdoor pants.

Development of indirect method for clothing pressure measurement using three-dimensional imaging

A direct measurement method using an air-pack-type pressure sensor has been used widely to obtain clothing pressure, but this method still has many limitations. For instance, it gives only pointwise information and is inherently inconvenient and error-prone. Therefore, we suggest an indirect method for measuring the clothing pressure of various positions at once without touching the subject by using three-dimensional (3D) deformations of a reference shape (i.e., a circle grid) printed on clothing. The clothing pressure can be obtained with a simple analysis of tensile stress and the curvature data extracted from the 3D deformation of circle grids on the clothing surface. Specifically, the tensile stress of the fabric was obtained from a tensile tester and the direction of the principal stress and the radius of curvature in the principal direction were measured from 3D imaging data to obtain an accurate value. The clothing pressure from the indirect method was verified by comparing the results from direct pressure measurements using an air-pack-type pressure sensor. The indirect method was found to successfully estimate the clothing pressure.

Development and Performance Evaluation of Body Armor for Wear Comfort Enhancement

This study helps develop a cool body armor that maintains a tight-fit configuration to the body surface and evaluates the performance of newly developed body armor in a wear test. Three types of body armor were used for evaluation. One was a tight fitting body armor that was constructed to improve the degree of fit and ease of movement for Korean soldier using 3D technology. Another was ventilating body armor with attached spacers on the shoulder to reduce the thermal stress on the soldier. The third was a prevail- ing body armor produced by a Korean body armor company. In order to evaluate the performance of the body armor, a human wear test, a thermal mannequin test, and computational fluid dynamics (CFD) were executed. Five subjects participated in the wear test. Subjective wear sensation, total amount of sweat and dynamic change of clothing microclimate were observed during and after exercise on a treadmill; subse- quently, it was found that subjects rated tight fitting body armor and ventilating body armor lighter, drier, and easier to move than the conventional body armor (p<.05). Total amount of sweat was the least in the case of ventilating body armor. The thermal resistance and vapor resistance of the ventilating body armor were improved remarkably. In addition, the skin temperature of the ventilating body armor with spacers was lower than the tight fitting body armor by at least 1 o C in the CFD result. It is noted that thermal-wet comfort of the 3D body armor with ventilating feature is superior to the conventional body armor, espe- cially when the ventilating channel is not closed due to a backpack.

Use of three-dimensional technology to construct ergonomic patterns for a well-fitting life jacket of heterogeneous thickness

To produce a life jacket that fits users both comfortably and stably, we developed a life jacket pattern based on the three-dimensional (3D) shape of the human body, with foam flotation material of different thicknesses used in different sections to achieve the required buoyancy and facilitate movement. We created a nonstandard life jacket for water sports that can adopt free design for canoeing and kayaking. Engineering design process and 3D technology were used to create the ergonomic 3D life jacket, which comprised an inner pattern, a polyethylene (PE) foam pattern for proper buoyancy in water, and the outer pattern. We developed a layering method for achieving the heterogeneous thickness of the life jacket and its outer pattern considering the ergonomic aspects of the 3D human body curvature and movability. The pattern expansion length was calculated to enlarge the outer pattern of each panel covering the varying thicknesses of life jacket and spacing for torso flexion. The calculation formula for this length was useful in increasing or decreasing the life jacket’s buoyancy, which was affected by the PE-foam thickness. Human-subject wear tests were performed in air and water to evaluate the developed life jacket. The developed life jacket had improved functionality. Significant differences (P ≤ 0.01) existed between the newly developed and conventional life jackets in air, in terms of the overall comfort, freedom of rowing movement, and fits in the chest and waist areas. Significant differences (P ≤ 0.05) also existed in water in terms of the overall fit and prevention of separation from the shoulder due to buoyancy.

A Study on Based on the Possibility of Quantitative Analysis using Virtual Clothing Simulation according to Raglan Sleeve Pattern Types

Abstract The purpose of this study was to explore effects of pattern alteration using a virtual clothing simulation approach in combination with 3D analysis software. Three raglan sleeves of different patterns were worn by an avatar using virtual clothing simulation with silk and cotton as the test fabrics. It was observed that the silhouette and hemline shape were affected differently based on raglan sleeve pattern and fabric type. By examining clothing pressure distribution, the cotton fabric designs and pattern shapes provided for a variety of influences on armhole and bust regions as well as the back sleeve area. For representative locations, cross section circumstance, cross section area, and volume were measured by using 3D analysis and the resulting correlation between the 2D and 3D data were investigated. Among different fabrics, there was little difference between the 2D and 3D clothing surface area. However, when using 3D analysis, clothing volume was significantly affected by different fabrics and pattern types. By simultaneously adopting the virtual simulator and 3D analysis, quantitative assessment of virtual clothing simulation was successfully conducted. In light of the results of this study, the resulting methodology is expected to be used as a comprehensive evaluation tool for virtual clothing simulation wear testing.

Basic Pattern Development of Haptic Gloves from 3D Data

Tight fitting glove pattern is necessary to convey oscillation to the skin from the sensors attached on the hands as found in the haptic device. However, it has been difficult to provide customized glove pattern for haptic device so far. The objective of the paper is to develop a 2D pattern that fit tightly to hands by adopting the recent 3D technology to the clothing science. In this study, the user graphic interface application software(2C-AN) for the semi-automatic garment pattern generation has been utilized to develop the methodology of construct tight-fitting glove pattern for the hand in natural position. A basic pattern was developed directly from the 3D images of hand and the verification of the proposed pattern was also provided.

Compression pants with differential pressurization: Kinetic and kinematical effects on stability

Clothing pressure is a very important variable in compression garments that is frequently omitted in other studies, despite the possibility of altering the experimental design and results. Most studies focus on testing the effects of released products rather than on how to design them. The aim of this study is to identify methods to increase stability of an extremity by developing compression pants with a design that assigns differential pressurization. CP1 (clothing pressure knee region: 0.95–1.03 kPa), which reinforces the knee joint, and CP2 (clothing pressure knee region: 1.67–2.12 kPa), which reinforces the knee joint and hamstring, are developed. In addition, CCP (clothing pressure knee region: 0.44–0.58 kPa) was developed as a control garment. Seven subjects wearing CP1, CP2, or CCP, performed single-leg landing from 40 cm height, for motion analysis. As a result, the angular velocity of the hip and knee, as well as the knee joint range of motion was increased significantly when CP1 are worn. Therefore, CP1 is efficient in absorbing the energy of the impact, making it much practical in terms of stability. The peak vertical ground reaction force showed little difference when different design of compression pants were tested. Meanwhile, CP2 significantly increases the knee moment. It is important to add that even a subtle manipulation of the level, location, or the method of pressurization significantly changes the stability of joints and the performance of exercise. This research shows that the functions of compression garments differ according to the level of pressurization and differential pressurization.

A Novel Method for 3D Surface and Solid Construction Analysis of Fabric Microstructure

In-depth knowledge of fabric microstructure is essential for understanding clothing comfort since it plays a significant role in heat and mass transfer between the human body and clothing. In this study, a novel method was employed for investigating 3D surfaces and solid construction characteristics of specific fabrics by using a reverse engineering technique. The surface construction data were obtained by a confocal laser scanning microscope and then manipulated by a 3D analysis program. Triangle mesh was used for connecting each 3D point, with clouds and fabric surface characteristics created by rendering techniques. For generating a 3D solid model, determinants of radius of curvature was used. According to the proposed method, actual surface expression of the real fabric was achieved successfully. The results from this methodology can be applied to the detailed analysis of clothing comfort that is highly influenced by the microstructure of the fabric.

The Change of Clothing Insulation and Surface Temperature Measured by Thermography with the Ease of Pattern

Effects of the ease of pattern on the thermal conditions of clothing were investigated through the measurement of clothing surface temperatures using infrared thermography. Four vests with different pattern ease were worn by five male subjects. Surface temperature distribution on the clothing were then examined using a thermogram to view thermo-regulating characteristics affected by the ease of pattern. Representative surface temperatures were calculated based on the percentage of the surface area within a certain temperature range and the midpoint value of the corresponding area. Representative surface temperatures matches well to the thermal insulation value measured by thermal manikin. Results indicated that representative surface temperature could be a useful quantitative value if some simple calculations were to be used alongside accurate image processing.

Development of 3D patterns for functional outdoor pants based on skin length deformation during movement

Purpose The seams of slim fit outdoor pants can be uncomfortable or even restrict body movement. To reduce discomfort, the authors need to determine optimal cutting lines in various designs that do not interfere with body movement. The purpose of this paper is to apply skin deformation mapping during movement to the ergonomic design of outdoor pants, focusing in particular on the 2D pattern generation of the crotch area in a 3D shape during movement. Design/methodology/approach A 3D shape and skin length deformation of the lower body were observed, including the crotch area, which is difficult to examine on the human body. To design ergonomic and streamlined outdoor pants, the authors selected seam lines where the changes in skin deformation are at their minimum based on the skin deformation mapping. In addition, the inseam along the medial thigh close to the crotch was removed to adjust the skin length of these areas, thereby increasing the extensible area of fabric necessary to adjust to a skin deformation. After selecting the seam lines, each of the 3D pattern blocks was generated by means of a 2D flattening method. In addition, the stress distribution of overlapped replica blocks along the crotch line during the 2D flattening process is a main independent factor to avoid deteriorating lower body movement as well as a good appearance. Findings Based on the results of skin deformation mapping of a human subject, this study suggested that it is best that the design line crosses where there is no skin deformation possible. And the pants were developed without the inner seam line at the upper medial thigh because of skin deformation of a large range of ±6 percent in the upper medial thigh during a 90° knee flexion or in the squatting down position. In a wear test, the developed 3D pattern without an inseam was rated higher than that with an inseam. This verified that removing the inseam, to prevent skin deformation of the medial upper thigh during knee flexion and squatting, is a logical decision. Regarding the correction of the overlapping area during arrangement of the replica, the appearance of the front of the pants was improved when 80 percent of the overlapping area was distributed near the point of the error source, which is the front of the male’s crotch line. Originality/value In this study, the crotch area, which has been difficult to observe in previous studies, were observed thoroughly and it was found that the length of the crotch curve did not increase during movement. In addition, skin deformation was mapped during a 90° knee flexion or in the squatting down position. It is expected that the overall process of developing 3D streamlined outdoor pants from 3D skin deformation mapping can be expanded to the development of patterns for other customized functional pants.